Donald Trump Jr.’s wife, Vanessa Trump, was hospitalized Monday after receiving a letter containing white powder that was later deemed to be non-hazardous, New York City police told Fox News.

President Trump‘s daughter-in-law opened the letter addressed to Donald Trump Jr. just after 10 a.m. at the couple's Manhattan apartment. It's unclear what the "white powder" was, but authorities tested the substance and found it to be "non-hazardous."

Vanessa Trump was taken to the hospital as a precaution, police said. Two other people who were also exposed to the powder were taken to the hospital.

A hazmat crew was called to the scene and began decontamination procedures shortly after the incident.

Trump Jr. is the eldest son of the president. He married Vanessa in 2005. The couple has five children, though it was not clear if any were home at the time of the incident.